This invention relates to printing device like a printer and printing method. More specifically, this invention relates to a printing device for ejecting ink onto paper for printing, said device being able to carry out adequate printing according to type of the paper used, a printing method used in said device, and an intermediate holding mechanism having holders to be used for charging paper roll of paper used onto said printing device.
In general, said printing device comprises a plurality of ink flow paths provided in ink jet head and having each nozzle at its front end, ejecting elements for ejecting outwards ink contained in said respective ink flow paths, and electrical controller for electrically controlling said ejection elements.
When using electrostrictive vibrator as said ejecting element, at least a part of walls of said ink flow paths is formed by flexible materials, and said electrostrictive vibrator is mounted on said walls. Said vibrator is electrically controlled by a controller at a predetermined timing, thereby to decrease the cross section of said ink paths to eject outwards ink contained therein, thus printing on paper.
When using thermal head as said ejecting element, a thermal head is provided on walls of said ink flow paths. Particular heating elements of said thermal head are electrically activated at a predetermined printing timing controlled by electrically controlling means, thereby to cause thermal expansion of ink contained in ink flow paths and to eject ink therein onto paper for printing thereof.
Heretofore known type of said printing device having electrostrictive vibrator is described herein below with reference to FIG. 1 and FIG. 2.
With reference to FIG. 1, in front of a cylindrical platen 1, a pair of carriage shafts 2, 2 are provided in a direction parallel to the axis of said platen 1, and a carriage 3 is provided on said carriage shafts 2 in a reciprocating manner. Said carriage 3 has an ink jet unit 4 for full color printing mounted thereon.
As shown in FIG. 2, said ink jet unit 4 has thereon 4 ink jet heads 5 corresponding respectively to four colors for full color printing and located each against said platen 1. Each ink jet head 5 has corresponding nozzle 6, these nozzles 6 being arranged in parallel manner to each other and opposing to said platen 1 as shown in FIG. 2. Said ink jet heads 5 are fixed on a head mounting member 7 which is in turn supported by said carriage 3.
A plurality of inlets 9 containing each auxiliary tanks 8 as buffer tanks for communicating with said respective nozzles 6 provided in said ink jet heads 5 are mounted on said carriage 3 behind said respective ink jet heads 5. Said respective inlets 9 are communicating with respective ink cartridges 10 of corresponding colors mounted detachably on said carriage 3.
On the outer side of one end of said platen 10, there is provided a pump unit 11 which is used for covering said nozzles 6 when not used to prevent ink therein from evaporating and for removing air bubbles or foreign substances stacked in said nozzles 6. Said pump unit 11 has a casing 13 having an opening 12 on the side of said carriage 3, said opening 12 having herein a cap body 14 which is reciprocally movable in the direction of said ink jet unit 4. Said cap body 14 has a plurality of openings 15 formed in a vertical oblong form so as to cover corresponding ink jet heads 5. Said each opening 15 has therein a gum liner 16, said liner 16 projecting outside from inside of circumference of said opening 15 to be pressed onto the circumference of corresponding ink jet head 5 in a airtight manner.
Said ink jet heads 5 comprises a plurality of ink flow paths 17 arranged in parallel and communicating with respective nozzles 6, each of said ink flow paths 17 having thereon corresponding piezo electric elements 18 as electrostrictive vibrators for ejecting ink from the front end of respective nozzles 6.
On the one hand, said cap body 134 of pump unit 11 has an approximately semispherical protrusion 19 provided on the front upper side thereof, and an air pressure channel 20 is formed from the summit of said protrusion 19 up to the rear side surface of said cap body 14, a pressurizing means such as pump (not shown) being connected to said air pressure channel 20. Said respective openings 15 of said cap body 14 is communicated with venting valves (not-shown) through communicating channels 22. Further, said respective openings 15 are provided with fluid exhausting pipes 23. These exhausting pipes 23 are connected to corresponding absorbing means such as pumps (not-shown) which absorb remaining portion of ink from respective opening 15 to be stored in a waste ink tank (not-shown).
On the other hand, an air pressure channel 25 is provided on the upper portion of side surface of said head mounting member 7 opposing to said pump unit 11, said air pressure channel 25 being used for receiving said protrusion 19 in a nozzle touch manner therein to communicating with said pressure air channel 20 when said pump unit 11 covers said ink jet unit 4. Said air pressure channel 25 is further branched into four branch channels 26 corresponding in number to said ink cartridges 10. The end portion of said respective branch channels 26 is connected to air pipes 27 communicating respectively with the upper portion of respective ink cartridges 10.
In the construction as described above of heretofore known printing device, said cap body 14 of said pump unit 11 is first put aside when printing, and said carriage 3 mounting said ink jet unit 4 is run along said platen 1, while at the same time said piezo electric elements 18 of said nozzles 6 for printing use are driven by feeding electricity thereto on the basis of predetermined printing signals, thereby feeding ink from said ink cartridges 10 through said inlets 9 into said ink flow paths 17 and ejecting through said nozzles 6 onto printing paper on said platen.
In general, the coloring materials used in ink for printing devices are divided into two types, that is dyestuff and pigment. The dyestuff type is superior to said pigment type in the freshness of colors while rather weak when exposed to water and light. On the other hand, said pigment type is inferior to said dyestuff type in freshness of colors while strong against water and light.
With respect to printing paper, there are two types of papers, one type being easier to absorb or receive ink and the other type being rather hard to receive ink. In the former type of paper, absorbed ink is more rapidly diffused, so that the total amount of ink used is less than that of the latter type of paper which is more hard to absorb ink. However, the former type of paper which absorbs more easily ink has inferior to the latter type due to said ink diffusion phenomenon.
Since ink and paper have different physical characteristic as described above, it must be advantageous to use different types of ink and paper in a single printing apparatus thereby to settle different printing conditions for obtaining a wide variety of printing.
However, only one type of ink could be used in the heretofore known printing devices.
This is because the upper limits of electricity feeding conditions such as voltage and frequency for driving ink jet head are different for different types of coloring agent used in an ink even when physical characteristics such as viscosity and surface tension of ink are held constant, so that, if driving pressure and frequency corresponding to the type of coloring agent are not used for driving ink jet head, a constant direction of ink ejection can not be obtained, resulting in a poor printing quality.
Further, with respect to the type of paper used, only a particular type of paper can be used for a particular ink used due to variations of printing quality caused by the absorbing capacity of ink used.
Table 1 shows the results of a printing test on various types of paper using a dyestuff type ink in the conventional printing device.
As shown in Table 1, any type of paper such as fine type, back print type and cloth could be printed with good result in a standard printing mode by using a dyestuff type of ink.
Table 2 shows a printing test on various types of paper using pigment type of ink in a heretofore known printing device.
As shown in Table 2, when printing was carried out using a pigment type ink at standard printing mode, good printing could not obtained on any type of paper. This is due to the fact that said ink jet heads 6 were driven at the same electricity feeding conditions as those in the case using dyestuff type ink in spite of using herein pigment type ink in place of dyestuff type ink, with the results that the ejection direction of ink was not constant and ink could not ejected.
With respect to paper used in this test, ink was not absorbed into paper at places having higher ink concentration when using a fine type paper. When using back print type paper, black ink was so much absorbed in this type of paper, with the result that only black color had a low concentration. Lastly, when using cloth as printing paper, all of four color lines have been absorbed too much into paper, with the result of four colors having each lower concentration.
In general, users of printing device have input the type of paper used into printing device by any means. One of these means has been setting of the type of paper on the operating panel of printing device by user. More recently, the information about type of paper to be used is often transferred into printing device from personal computer together with printing data. In the last case, user selects his desired type of paper from Paper Menu printed on a software called Printer Driver containing types of paper such as common paper, coat paper, film for a overhead projector (OHP), back print film, burnished paper and the like.
On the other hand, while there are several cases where one can easily discriminate paper used by means of appearance thereof and touch feeling thereon, there are so many papers which have resembling appearance and feeling. Therefore, when users set erroneously types of paper, printing can not be carried out at printing conditions adapted to the type of paper used, resulting in undetected printing quality.
While it is possible to discriminate types of paper used through its factors such as surface roughness, light transparency and rigidity, but it is not practical to mount detection mechanism for that purpose upon printing device, because one detection device is necessary for anything of said paper factors, thus increasing considerably the cost of printing device. When detecting type of paper using the factor of light transparency, only three states of paper, i.e. transparent, translucent and opaque, which limits adoptation to more and more various types of paper. As described above, direct detection of paper type has been difficult in technical and economical view points.
Accordingly, this invention has as its object to deliver a printing device which can carry out always a high quality of printing while taking into consideration the types of ink and paper used, and having a means for automatically detecting the type of paper, and a printing method using said printing device as well as an intermediate holder for charging a roll of paper to be used into the printing device.
A printing device for printing on a supplied paper described in claim 1, said printing device being provided therein with ink ejecting elements for ejecting ink from ink flow channel having nozzles on its front end and formed in ink jet head, and with a controlling means for electrically controlling said ink ejecting elements, is characterized in that said controlling means is constructed such that electric controlling conditions with respect to said ink ejecting elements are varied according to types of ink used. Such a construction of printing device allow for driving its ejecting components with a good driving conditions adapted to type of ink, thereby to deliver ink in a stable manner to carry out good quality of printing.
A printing device according to claim 2 is characterized in that said electric controlling means is such that image processing depending on ink ejecting number from nozzles is varied correspondingly to type of paper used. Such a construction allows for image processing adapted to type of paper thereby to carry out good quality of printing.
A printing device according to claim 3 is characterized by a paper roll holding mechanism for holding said paper roll by means of holders attached to both end portions of a roll of said paper, by a holder engaging member which is movable and can be applied onto peripheral surface of one of said holders of said paper roll held by said paper roll holding mechanism, by a paper type detection unit for detecting type of said roll paper according to the position of said holder engaging correspondingly to outer diameter of said holder representing type of said roll paper used, and by roll paper discriminating means for discriminating type of roll paper based on said paper type detection unit. In such a construction, said paper type detection means can automatically detect type of paper only by mounting a holder, outer diameter of which is adapted to type of roll paper.
A printing device according to claim 4 is characterized by a plurality of fixed sensors outputting each switching signals, and by state setting member for setting said respective sensors at open or close state correspondingly to stopped position of said holder engaging member. With such a construction of printing device, type of paper can be detected by combination of switching signals output from respective sensors.
A printing device according to claim 5 is characterized by a paper roll holding mechanism for holding said paper roll by means of holders attached to both end portions of a roll of said paper, by a paper type detection unit for detecting type of said roll paper according to color element of said holder representing type of said roll paper used, and by roll paper discriminating means for discriminating type of roll paper based on said paper type detection unit. With such a construction, type of roll paper can be detected by means of color element of holder.
A printing device according to claim 6 is characterized in that said paper type detection unit is composed of sensors which discriminate at least one of two factors, i.e. color type and color concentration of color applied on peripheral surface of said holder. Thus, it is possible to detect type of roll paper by means of color and its concentration of color element of said holder.
A printing device according to claim 7 is characterized by a paper roll holding mechanism for holding said paper roll by means of holders attached to both end portions of a roll of said paper, by a holder engaging member which is movable and can be applied onto peripheral surface of one of said holders of said paper roll held by said paper roll holding mechanism, by first paper type detection unit for detecting type of said roll paper according to the position of said holder engaging member located correspondingly to outer diameter of said holder representing type of said roll paper used, second paper type detection unit for detecting type of said roll paper according to color of said holder representing type of said roll paper used, and by roll paper discriminating means for discriminating type of roll paper based on both outputs of said first and second paper type detection units.
Further, said printing device according to claim 8 is characterized in that said first paper type detection unit comprises a plurality of fixed sensors outputting each switching signals, and by state setting member for setting said respective sensors at open or close state correspondingly to stopped position of said holder engaging member, and said second paper type detection unit comprises sensors which discriminate at least one of two factors, i.e. color type and color concentration of color applied on peripheral surface of said holder. Thus, said state setting members set respective sensor of said first paper type detection unit in open state or in close state according to stopped position of said holder engaging member, while sensors of said second paper type detection unit reads out color elements which are different correspondingly to paper type, so that type of paper can be detected by combination of said open and close signals from respective sensors and color elements of holders.
A printing device according to claim 9 is characterized by a cover member which is opened when exchanging said paper roll and a driven member which is driven by said opening operation of said cover member so as to shift said holder engaging member into a retraction position where it can not engage with said holder. A printing device according to claim 10 is characterized in that said holder engaging member engages with outer peripheral surface of holder body. A printing device according to claim 11 is characterized in that said holder engaging member engages with outer peripheral surface of a flange formed on said holder body. Under such a construction, it is possible to use both holder body itself and its flange as discriminating element of roll paper.
A printing device according to claim 12 is characterized in that different color inks are ejected from a plurality of ink jet heads. Thus, it is possible to adapt color printing to type of ink and/or paper used thereby to obtain a good quality of printing.
A printing method for printing on paper wound in the form of paper roll according to claim 13 is characterized by the steps of storing printing conditions for a plurality of paper types, discriminating type of paper used by reading discriminating elements provided on said paper roll, and carrying out printing based on corresponding printing conditions. Thus, it is possible to discriminate paper type upon mounting paper roll onto printing device without use of complicated structure of printing device and without the need of rotating paper roll.
Further, printing method claimed in claim 14 is characterized in that said discriminating element is single, type of paper is discriminated by said single discriminating element, and printing is carried out based on printing conditions corresponding to said discriminated paper. Further, a printing method claimed in claim 15 is characterized in that outer diameter of at least one of said holders mounted on paper roll is used as said discriminating element. Further, a printing method claimed in claim 16 is characterized in that color element of at least one of said holders mounted on paper roll is used as said discriminating element. A printing method claimed in claim 17 is characterized in that said color element comprises at least one of color and color concentration of said holder. A printing method claimed in claim 18 is characterized in that a plurality of said discriminating elements are used, wherein type of paper is discriminated by combination of said plurality of discriminating elements, and printing is carried out based on printing conditions corresponding to said detected paper type. Further, a printing method claimed in claim 19 which is characterized in that said plurality of discriminating elements comprise outer diameter of at least one of holders mounted on said paper roll and color elements of said holder. Further, a printing method claimed in claim 20 is characterized in that said color element comprises at least one of color and color concentration of said holder. Thus, it is possible to automatically detect type of roll paper by means of outer diameter and color element of holder and to increase the number of detectable paper types by increasing the number of discriminating elements.
An intermediate holding mechanism described in claim 21 having holders for charging paper roll comprising a core and roll paper wound on said core onto said printing device is characterized in that said holders are mounted concentrically on at least one end of said core, and that combination of outer diameter and color of peripheral surface of said holder is varied correspondingly to type of said roll paper. Thus, it is possible to detect types of various papers by means of paper type detection unit.
Further, an intermediate holding mechanism claimed in claim 22 is characterized by further auxiliary holders fitted into said holder for mounting said paper roll on said paper roll holding mechanism. Thus, it is possible to use auxiliary holder of the same shape when charging paper roll onto printing device thereby to obtain more stable charging of paper roll on printing device.